#include <iostream>
using namespace std;
class Point
{
protected:
    int x, y;

public:
    Point(int a, int b = 0)
    {
        x = a;
        y = b;
        cout << "constructing point(" << x << "," << y << ")" << endl;
    }
};
class Line : public Point
{
protected:
    int len;

public:
    Line(int a, int b, int l) : Point(a, b)
    {
        len = l;
        cout << "Constructing Line,len ..." << len << endl;
    }
};
int main()
{
    Line L1(1, 2, 3);
    system("pause");
    return 0;
}